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Results for “Continuous Evolution”

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PubMed2000

Vocal responsiveness in male wild chimpanzees: implications for the evolution of language.

Several captive chimpanzees and bonobos have learned to use symbols and to comprehend syntax. Thus, compared with other nonhumans, these animals appear to have unusual cognitive powers that can be recruited for communicative behavior. This raises the possibility that wild chimpanzee vocal communication is more complex than heretofore demonstrated. To examine this possibility, I investigated whether wild chimpanzee vocal exchanges exhibit uniquely human conversational attributes. The results indicate that wild chimpanzees vocalize at low rates, tend not to respond to calls that they hear, and, when they do respond, tend to give calls that are similar to the ones they have heard. Thus, chimpanzee vocal interactions resemble those of other primate species, and show no special similarity to human conversations. The results support the view that we need to explore cognitive and social continuities and discontinuities with nonhuman primates to understand the origin and evolution of language, but also emphasize the need for fine-grained analyses of wild chimpanzee vocal interactions.

Animals↗

PubMed2004

Effects of neighbourhood size and connectivity on the spatial Continuous Prisoner's Dilemma.

The Prisoner's Dilemma, a two-person game in which the players can either cooperate or defect, is a common paradigm for studying the evolution of cooperation. In real situations cooperation is almost never all or nothing. This observation is the motivation for the Continuous Prisoner's Dilemma, in which individuals exhibit variable degrees of cooperation. It is known that in the presence of spatial structure, when individuals "play against" (i.e. interact with) their neighbours, and "compare to" ("learn from") them, cooperative investments can evolve to considerable levels. Here, we examine the effect of increasing the neighbourhood size: we find that the mean-field limit of no cooperation is reached for a critical neighbourhood size of about five neighbours on each side in a Moore neighbourhood, which does not depend on the size of the spatial lattice. We also find the related result that in a network of players, the critical average degree (number of neighbours) of nodes for which defection is the final state does not depend on network size, but only on the network topology. This critical average degree is considerably (about 10 times) higher for clustered (social) networks, than for distributed random networks. This result strengthens the argument that clustering is the mechanism which makes the development and maintenance of the cooperation possible. In the lattice topology, it is observed that when the neighbourhood sizes for "interacting" and "learning" differ by more than 0.5, cooperation is not sustainable, even for neighbourhood sizes that are below the mean-field limit of defection. We also study the evolution of neighbourhood sizes, as well as investment level. Here, we observe that the series of the interaction and learning neighbourhoods converge, and a final cooperative state with considerable levels of average investment is achieved.

Animals↗

PubMed1997

Cognition and life: the autonomy of cognition.

In this paper we propose a philosophical distinction between biological and cognitive domains based on two conditions that are postulated to obtain a useful characterization of cognition: biological grounding and explanatory sufficiency. According to this, we argue that the origin of cognition in natural systems (cognition as we know it) is the result of the appearance of an autonomous system embedded into another more generic one: the whole organism. This basic idea is complemented by another one: the formation and development of this system, in the course of evolution, cannot be understood but as the outcome of a continuous process of interaction between organisms and environment, between different organisms, and, specially, between the very cognitive organisms. Finally, we address the problem of the generalization of a theory of cognition (cognition as it could be) and conclude that this work would imply a grounding work on the problem of the origins developed in the frame of a confluence between both Artificial Life and an embodied Artificial Intelligence.

Animals↗

PubMed1994

Advances in the theory and practice of DNA-hybridization as a systematic method.

DNA hybridization continues in the 1990s to provide insight into phylogeny and evolution. The resilience of this 30-year-old distance technique may be attributed to its fundamental power as a comparative method, as well as to advances in our understanding of its operation and improvements in experimental design and data analysis. These attributes and advances, along with the assumptions and limitations of DNA hybridization, are discussed in this paper. Examples are provided of recent DNA hybridization studies of molecular, morphological, and behavioral systematics and evolution.

Animals↗

PubMedDate not supplied

General internal medicine practice trends in large multispecialty clinics.

OBJECTIVE: To assess practice trends in the general internal medicine departments of large multispecialty clinics. DESIGN: A survey questionnaire addressing the following issues: 1) department size and rate of growth, 2) services provided, 3) patient population, 4) individual clinical workload, 5) call arrangements, 6) time away from practice, and 7) benefits and salary. PARTICIPANTS: 22 multispecialty clinics, with a mean of 279 physicians. MEASUREMENTS AND RESULTS: Mean general internal medicine department physician expansion was 28% over the preceding three years. Primary care, clinic system access, care of patients laterally shifted from subspecialty internists, and preoperative evaluations were the four major services provided. The mix of fee-for-service, Medicare/Medicaid, and prepaid-plan patients was diverse. Mean outpatient clinical scheduling was 35 hours per week exclusive of hospital practice, administrative time, and paperwork. Study of call arrangements revealed a definite trend toward a group practice model of shared responsibility during the day as well as nights and weekends. Mean meeting and vacation time was 35 days per year. Salary was set by committee, formula, or both. Department stresses and dissatisfactions were also reported. CONCLUSIONS: Rapid expansion of general internal medicine departments and services will continue as subspecialists back away from providing primary care. The evolution of general internal medicine practice must be anticipated and managed for optimal patient and departmental outcomes.

Ambulatory Care Facilities↗

PubMed2002

Metabolic flux redistribution in Corynebacterium glutamicum in response to osmotic stress.

Osmotic stress constitutes a major bacterial stress factor in the soil and during industrial fermentation. In this paper, we quantified the metabolic response, in terms of metabolic flux redistribution, of a lysine-overproducing strain of Corynebacterium glutamicum grown under continuous culture, to gradually increasing osmolality. Oxygen and carbon dioxide evolution rates, and the changes in concentration of extracellular, as well as intracellular, metabolites were measured throughout the osmotic gradient. The metabolic fluxes were estimated from these measurements and from the mass balance constraints at each metabolite-node of the assumed metabolic reaction network. Our results show that formation rates of compatible solutes--trehalose first and proline at a later stage of the gradient--increased with osmotic stress to equilibrate the external osmotic pressure. Estimated flux distributions indicate that the observed increase in the glucose specific uptake rate with osmotic stress is channeled through the main energy generating pathways-- glycolysis and the tricarboxylic acid cycle--while the flux through the pentose phosphate pathway remains constant throughout the gradient. This results in a significant increase in the net specific ATP production rate, which may possibly be used to support the higher energy requirements required for cellular maintenance at high osmolalities. Finally, nodal analysis confirmed that the PEP/pyruvate node is essentially rigid and that the glucose-6-phosphate, oxaloacetate and alpha-ketoglutarate nodes are flexible and therefore adaptable to changes in osmotic pressure in C. glutamicum.

Adenosine Triphosphate↗

PubMed2001

Retrotransposed genes such as Frat3 in the mouse Chromosome 7C Prader-Willi syndrome region acquire the imprinted status of their insertion site.

Prader-Willi syndrome (PWS) results from loss of function of a 1.0- to 1.5-Mb domain of imprinted, paternally expressed genes in human Chromosome (Chr) 15q11-q13. The loss of imprinted gene expression in the homologous region in mouse Chr 7C leads to a similar neonatal PWS phenotype. Several protein-coding genes in the human PWS region are intronless, possibly arising by retrotransposition. Here we present evidence for continued acquisition of genes by the mouse PWS region during evolution. Bioinformatic analyses identified a BAC containing four genes, Mkrn3, Magel2, Ndn, Frat3, and the Atp5l-ps1 pseudogene, the latter two genes derived from recent L1-mediated retrotransposition. Analyses of eight overlapping BACs indicate that these genes are clustered within 120 kb in two inbred strains, in the order tel-Atp5l-ps1-Frat3-Mkrn3-Magel2-Ndn-cen. Imprinting analyses show that Frat3 is differentially methylated and expressed solely from the paternal allele in a transgenic mouse model of Angelman syndrome, with no expression from the maternal allele in a mouse model of PWS. Loss of Frat3 expression may, therefore, contribute to the phenotype of mouse models of PWS. The identification of five intronless genes in a small genomic interval suggests that this region is prone to retroposition in germ cells or their zygotic and embryonic cell precursors, and that it allows the subsequent functional expression of these foreign sequences. The recent evolutionary acquisition of genes that adopt the same imprint as older, flanking genes indicates that the newly acquired genes become 'innocent bystanders' of a primary epigenetic signal causing imprinting in the PWS domain.

Animals↗

PubMed2006

Patient satisfaction with psychotropic drugs: sensitivity to change and relationship to clinical status, quality-of-life, compliance and effectiveness of treatment. Results from a nation-wide 6-month prospective study.

OBJECTIVE: To see if patient satisfaction with psychotropics (PSP) could be used as a patient-oriented outcome variable in the evaluation of PSP drugs in clinical epidemiological studies, relationships between PSP, clinical status, QoL, compliance and the type of antipsychotic were analyzed. Elements of validation of PSP were also assessed. METHOD: In a 6-month prospective study, 933 schizophrenic outpatients with initiation or change to their antipsychotic treatment were enrolled. Psychiatrists completed five CGI-SCH scales (positive, negative, cognitive, depressive and global), hospitalization, compliance, and prescription variables. Patients completed PSP, EuroQoL scales, sexual function and compliance variables. RESULTS: A satisfactory structural equation model was obtained showing significant relationships PSP/compliance (coef.=0.16), QoL/PSP (coef.=0.37), clinical status/QoL (coef.=0.61), clinical status/compliance (coef.=0.09). Patients receiving olanzapine were more satisfied than patients receiving other atypicals (coef.=012) and had better clinical status than patients treated with typicals (coef.=0.08). Evolution of PSP was related to clinical status, QoL, and continuation of treatment (all P<001). Sensitivity to change of PSP was moderate (effect size=0.2). CONCLUSION: PSP produced consistent results in relation to validated outcome variables. However, a single-item measure was not sufficiently sensitive to change. Multi-item questionnaires evaluating different dimensions are needed.

Adult↗

PubMed2006

Vaccinal control of Marek's disease: current challenges, and future strategies to maximize protection.

Marek's disease is an economically important lymphoid neoplasm of chickens, caused by oncogenic strains of Marek's disease herpesvirus. The disease can be successfully controlled by vaccination with attenuated or non-pathogenic MDV strains. However, vaccine failures do occur as field strains continue to evolve towards pathotypes of greater virulence, and this evolution is likely to be driven by the vaccines themselves. Two general strategies can be considered to improve protection by vaccination. Firstly by the development of novel vaccines, and secondly by maximizing the potential of existing vaccines. This second goal requires investigation of optimal timing and vaccine delivery route, and optimal vaccination regimes for different breeds of chick. Accurate quantitation of Marek's disease vaccine virus in vaccinated chicks will contribute significantly to our understanding of vaccinal protection. We recently developed a real-time polymerase chain reaction (PCR) assay for quantitation of CVI988 vaccine virus in the feather tips, a rich source of viral DNA which can easily be sampled in a non-invasive manner. This PCR test is now used commercially to confirm the successful vaccination of chicks. We have also used the PCR to examine various aspects of vaccination in experimental chicks and commercial chicks with a view to determining how vaccine level in feathers correlates with protection against challenge, and for identifying optimal timing and vaccine delivery route, and optimal vaccination regimes for different breeds of chick. In this article we review some aspects of the current vaccinal control of Marek's disease, before highlighting some of the problems associated with current vaccines and vaccination strategies, and the challenges for the future. We go on to discuss the development and use of our real-time PCR feather test, its current applications and potential opportunities in Marek's disease vaccine research.

Animals↗

PubMed2000

Past and future technologic developments for rhythm and conduction disturbances.

Since the first cardiac pacemaker was implanted in 1958, continuing technologic innovations have steadily improved the therapeutic power of implantable cardiac device therapy. This evolution has benefited both patients and their physicians, expanding the conditions manageable through pacing and implantable defibrillation while streamlining implant and follow-up procedures. This progress is likely to continue unabated because (1) devices will continue to grow smaller; (2) more advanced features will be introduced, with an increased level of automaticity; and (3) the quality and quantity of telemetered diagnostic information about both patient and device will continue to expand, and device sophistication will soon reach the point at which prediction and prevention of specific events will be a reality. This article reviews historical developments and presents concepts that are guiding future technologic innovations.

Arrhythmias, Cardiac↗

PubMed2004

Epidemiological and genetic analysis of severe acute respiratory syndrome.

The severe acute respiratory syndrome (SARS) epidemics in 2002-2003 showed how quickly a novel infectious disease can spread both within communities and internationally. We have reviewed the epidemiological and genetic analyses that have been published both during and since these epidemics, and show how quickly data were collected and analyses undertaken. Key factors that determine the speed and scale of transmission of an infectious disease were estimated using statistical and mathematical modelling approaches, and phylogenetic analyses provided insights into the origin and evolution of the SARS-associated coronavirus. The SARS literature continues to grow, and it is hoped that international collaboration in the analysis of epidemiological and contact-network databases will provide further insights into the spread of this newly emergent infectious disease.

China↗

PubMed1999

Glass transition of wheat gluten plasticized with water, glycerol, or sorbitol.

The glass transition temperature of wheat gluten, plasticized with water, glycerol, or sorbitol, has been studied using dynamical mechanical thermal analysis. For the three plasticizers studied, the general behavior of the glass transition temperature broadly followed the Couchman-Karasz relation using a wheat gluten DeltaC(p)() of 0.4 J g(-)(1) K(-)(1). Compared on such a fractional weight basis, it could be concluded that the plasticizing effect of glycerol and sorbitol on wheat gluten proteins is less important than the plasticizing effect of water. A continuous curve was obtained with the three plasticizers when the evolution of the glass transition temperature was presented on a fractional molecular basis. This was related to the similar chemical structure of these three components containing hydroxyl groups.

Calorimetry, Differential Scanning↗

PubMed2004

Insertion and partition of sodium taurocholate into egg phosphatidylcholine vesicles.

PURPOSE: To get a continuous description of the insertion and partition processes of sodium taurocholate (TC) into the lipid bilayers of vesicles that can serve as a model for understanding the mechanism of destabilization by the bile salts of liposomes used as drug carriers for oral administration. METHODS: The progressive solubilization of egg phosphatidylcholine vesicles during TC addition at controlled rates was followed by continuous turbidity (OD) and resonance energy transfer (RET) between two fluorescent probes. The influence of the lipid and TC concentrations as well as the rate of TC addition on the processes were examined. RESULTS: Continuous turbidity recordings allowed following of the size and composition evolutions of the mixed TC/lipid aggregates formed at different steps of the vesicle-micelle transition. The solubilization mechanism is governed by complex kinetics that depend on the surfactant concentration and its addition rate. A two-step process characterizes the evolution of the vesicular state: interaction of TC molecules with the external monolayer of the vesicles first occurs. The homogeneous distribution of TC within the lipid matrix after its insertion is a very slow process. A micellar structural reorganization is observed when TC is added rapidly. CONCLUSIONS: This work provides detailed information on the slow insertion and diffusion kinetics of TC in liposomal bilayers by using a dynamic study which mimics physiological phenomena of digestion.

Detergents↗

PubMed2007

The creation of an advance care planning process for patients with ESRD.

Comprehensive care of patients with end-stage renal disease (ESRD) requires expertise in advance care planning (ACP), including attention to ethical, psychosocial, and spiritual issues related to starting, continuing, withholding, and stopping dialysis therapy. ACP currently is under evolution from a document-driven decision-focused event. This article describes a new approach to ACP that emphasizes a relational patient-centered process that focuses on broader goals of care for a particular dialysis patient with known medical problems and is designed to serve as a guide to help nephrologists, social workers, and other health care professionals explore ACP discussions with their patients with ESRD. Specifically, we define ACP, highlight goals and key features of this facilitated ACP process, and provide an interview guide with examples of questions that can be used to explore the various aspects of ACP with patients and their families. Outcomes of such an ACP process will not be measured by increasing the number of completed advance directives, but by improving satisfaction with the entire end-of-life experience and having outcomes match patient preferences. It is expected that such a process will enhance shared decision making among patient, surrogate, and health care provider and help build strong and intimate relationships that can only serve to enhance end-of-life care. Throughout this process, patients are not abandoned as they confront the realities of declining health and functional status, but rather are supported through their illness and life on dialysis treatment.

Advance Care Planning↗

PubMed1973

Still more genetic variability in natural populations.

Heat-denaturation studies of xanthine dehydrogenase have revealed many more additional alleles at the locus controlling this enzyme than are revealed by electrophoretic studies. In natural populations of species in the virilis group of the genus Drosophila, heat-denaturation studies of flies from the same locality revealed 1.74 times as many alleles as did electrophoretic studies. Similarly, studies of several species over their geographic range also revealed 1.74 times as many alleles. In addition, for the nine species studied, electrophoretic analysis had revealed only 11 alleles within the group, whereas heat-denaturation studies revealed a total of 32 alleles. These findings are discussed in the light of the continuing controversy over Darwinian and non-Darwinian theories of evolution.

Aldehyde Oxidoreductases↗

PubMed2002

Engineering liver therapies for the future.

Treatment of liver disease has been greatly improved by the advent and evolution of liver transplantation. However, as demand for donor organs continues to increase beyond their availability, the need for alternative liver therapies is clear. Several approaches including extracorporeal devices, cell transplantation, and tissue-engineered constructs have been proposed as potential adjuncts or even replacements for transplantation. Simultaneously, experience from the liver biology community have provided valuable insight into tissue morphogenesis and in vitro stabilization of the hepatocyte phenotype. The next generation of cellular therapies must therefore consider incorporating cell sources and cellular microenvironments that provide both a large population of cells and strategies to maintain liver-specific functions over extended time frames. As cell-based therapies evolve, their success will require contribution from many diverse disciplines including regenerative medicine, developmental biology, and transplant medicine.

Animals↗

PubMed2001

Gene flow in wild chimpanzee populations: what genetic data tell us about chimpanzee movement over space and time.

The isolation of phylogenetically distinct primate immunodeficiency viruses from at least seven wild-born, captive chimpanzees indicates that viruses closely related to HIV-1 may be endemic in some wild chimpanzee populations. The search for the chimpanzee population or populations harbouring these viruses is therefore on. This paper attempts to answer the question of whether or not such populations of chimpanzees are likely to exist at all, and, if so, where they are likely to be found. We summarize what is known about gene flow in wild populations of chimpanzees, both between major phylogeographical subdivisions of the species, and within these subdivisions. Our analysis indicates that hitherto undocumented reproductively isolated chimpanzee populations may in fact exist. This conclusion is based on the observation that, despite limited geographical sampling and limited numbers of genetic loci, conventional notions of the nature and extent of chimpanzee gene flow have recently been substantially revised. Molecular genetic studies using mitochondrial DNA sequences and hypervariable nuclear microsatellite markers have indicated the existence of heretofore undocumented barriers to chimpanzee gene flow. These studies have identified at least one population of chimpanzees genetically distinct enough to be classified into a new subspecies (Pan troglodytes vellerosus). At the same time, they have called into question the long-accepted genetic distinction between eastern chimpanzees (Pan troglodytes schweinfurthii) and western equatorial chimpanzees (Pan troglodytes troglodytes). The same studies have further indicated that gene flow between local populations is more extensive than was previously thought, and follows patterns sometimes inconsistent with those documented through direct behavioural observation. Given the apparently incomplete nature of the current understanding of chimpanzee gene flow in equatorial Africa, it seems reasonable to speculate that a chimpanzee population or populations may exist which both harbour the putative HIV-1 ancestor, and which have remained reproductively isolated from other chimpanzee populations over the time-scale relevant to the evolution of the SIVcpz-HIV-1 complex of viruses. Continued extensive sampling of wild chimpanzee populations, both for their genes and their viruses, should be performed quickly considering the high probability of extinction that many wild chimpanzee populations face today. The history of human-chimpanzee contacts is discussed.

Africa↗

PubMed2006

Efficient quantum-state estimation by continuous weak measurement and dynamical control.

We demonstrate a fast, robust, and nondestructive protocol for quantum-state estimation based on continuous weak measurement in the presence of a controlled dynamical evolution. Our experiment uses optically probed atomic spins as a test bed and successfully reconstructs a range of trial states with fidelities of approximately 90%. The procedure holds promise as a practical diagnostic tool for the study of complex quantum dynamics, the testing of quantum hardware, and as a starting point for new types of quantum feedback control.

Journal Article↗